Method and apparatus for digesting pulp in rotating digesters



Dec. 22,1925 1,566,339 4 E. MORTERUD METHOD AND AiPARATUS FOR DIGESTING PULP IN ROTATING DIGESTERS Filed May 23. 1925 Patented Dec. 22, 1925.

rarest OFFICE.

EINAR MORTERUD, OF TOBDEROD, NEAR MOSS, NORWAY.

METHOD AND APPARATUS FOR DIGESTING PULP IN ROTATING DIGESTERS.

Application filed. May 28, 1925.

To all whom it may concern:

Be it known that I, EINAR MORTERUD, engineer, a subject of the King of Norway, residing at Torderod, near Moss, Norway, have invented certain new and useful Improvements in Methods and Apparatus for Digesting Pulp in Rotating Digesters, of which the following is a specification.

In the digestion of sulphate pulp in rotating digesters with indirect heating of the digesting liquid by means of a heating apparatus (calorisator) outside the digester it is known to take out the liquid through one trunnion passing it through the calorisator and returning the heated liquid to the digester through the other trunnion, the outlet tube opening in one end of the digester and the intake tube in the opposite end of the digester being stationary during the circulation of the liquid. In the digestion of sulphite pulp the indirect heating of the liquid has not been utilized in combination with rotating digesters.

The above mentioned processes do not utilize the rapid and thorough mixing of the pulp and the several parts of the heated liquid which is caused by the rotation of the digester, and this mixing is very important owing to the fact that the liquid entering the digester has a difi'erent temperature from the liquid leaving the same.

The present invention has for its object a process and a digester by means of which it is made possible to continuously circulate a. liquid heated outside the digester through the latter during the rotation, the location of the intake and outlet tubes for the sir culating heated liquid being so chosen as to cause the liquid to pass a considerable distance through the digester between the intake and outlet opening.

In the drawing:

Fig. 1 is a diagrammatic sectional view through a digester in accordance with the present invention.

Fig. 2 is a diagrammatic sectional view of a modified form of the invention, and

Figs. 3 and 4 are a cross section and longitudinal section respectively on a larger scale through a distributing device for the liquid conducted to and from the digester.

In Fig. 1 A is the digester, B is the Serial No. 33,580.

calorisator and C is the circulating pump.

9 is a gas tube passing into the digester through a trunnion and s is a sieve. u is the outlet tube and i the intake tube for the digesting liquid. These tubes both enter the digester through the second trunnion thereof, the intake tube being extended a. con siderable distance into the interior of the digester and directing the jet of heated digesting liquid against the opposite wall of the digester. Behind the sieve S surrounding the outlet tube the intake tube may have the form of an ejector tube so as to take with it part of the liquid which is about to leave the digester and has passed through the sieve S.

According to the form of the invention illustrated in Fig. 2 the intake and outlet tubes also enter the digester through the same trunnion. In this case, however, the tubes have their openings at opposite ends of the digester and are both provided with a sieve S. The arrangement in this case may be such that the two tubes operate alternately as intake and outlet tube, the lower tube being always the outlet tube.

For this purpose the rotating valve construction illustrated on Figs. 3 and 4 is utilized.

The hollow trunnion t of the digester is provided with a longitudinal axial wall n, dividing .the interior of the tube in two channels p, 7' of semi-circular cross section. 35 These semi-circular channels are provided with openings 0 through the wall of the hollow trunnion t and through this opening communicate with the outlet tube at and intake tube 5 which are provided in a stationary casing with k, surrounding the exterior end of the hollow trunnion 27.

As it will be understood the rotation of the digester trunnion -25 will alternately bring the channels 39, 1" in communication with intake tube *5 and outlet tube 24.

Claims 1. In a process for digesting pulp in rotating digesters by means of a digesting liquid circulated through the digester and through a calorisator outside the same, introducing the digesting liquid through one of the digester trunnions to a point-inside the digester at a considerable distance from said trunnion and taking the digesting liquid out of the digester through a channel in the same trunnion.

2. A rotating digester for Wood pulp having an intake and outlet channel for digest ing liquid located in one of its trunnions and tubes inside the digester connected with said intake and outlet channels and having their open ends located near the opposite ends of the rotating digester and means for 10 alternately connecting the channels in said trunnion With the intake and outlet tube from the caloi-isator, mounted outside the digester.

In testimony whereof I have signed my 15 name to this specification.

EINAR MORTERUD. 

